
/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>


static ngx_int_t ngx_enable_accept_events(ngx_cycle_t *cycle);
static ngx_int_t ngx_disable_accept_events(ngx_cycle_t *cycle);
static void ngx_close_accepted_connection(ngx_connection_t *c);


void
ngx_event_accept(ngx_event_t *ev)
{
  socklen_t          socklen;
  ngx_err_t          err;
  ngx_log_t         *log;
  ngx_socket_t       s;
  ngx_event_t       *rev, *wev;
  ngx_listening_t   *ls;
  ngx_connection_t  *c, *lc;
  ngx_event_conf_t  *ecf;
  u_char             sa[NGX_SOCKADDRLEN];
#if (NGX_HAVE_ACCEPT4)
  static ngx_uint_t  use_accept4 = 1;
#endif

  ecf = ngx_event_get_conf(ngx_cycle->conf_ctx, ngx_event_core_module);

  if (ngx_event_flags & NGX_USE_RTSIG_EVENT) {
    ev->available = 1;

  } else if (!(ngx_event_flags & NGX_USE_KQUEUE_EVENT)) {
    ev->available = ecf->multi_accept;
  }

  lc = ev->data;
  ls = lc->listening;
  ev->ready = 0;

  ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ev->log, 0,
                 "accept on %V, ready: %d", &ls->addr_text, ev->available);

  do {
    socklen = NGX_SOCKADDRLEN;

#if (NGX_HAVE_ACCEPT4)
    if (use_accept4) {
      s = accept4(lc->fd, (struct sockaddr *) sa, &socklen,
                  SOCK_NONBLOCK);
    } else {
      s = accept(lc->fd, (struct sockaddr *) sa, &socklen);
    }
#else
    s = accept(lc->fd, (struct sockaddr *) sa, &socklen);
#endif

    if (s == -1) {
      err = ngx_socket_errno;

      if (err == NGX_EAGAIN) {
        ngx_log_debug0(NGX_LOG_DEBUG_EVENT, ev->log, err,
                       "accept() not ready");
        return;
      }

#if (NGX_HAVE_ACCEPT4)
      ngx_log_error((ngx_uint_t) ((err == NGX_ECONNABORTED) ?
                                  NGX_LOG_ERR : NGX_LOG_ALERT),
                    ev->log, err,
                    use_accept4 ? "accept4() failed" : "accept() failed");

      if (use_accept4 && err == NGX_ENOSYS) {
        use_accept4 = 0;
        ngx_inherited_nonblocking = 0;
        continue;
      }
#else
      ngx_log_error((ngx_uint_t) ((err == NGX_ECONNABORTED) ?
                                  NGX_LOG_ERR : NGX_LOG_ALERT),
                    ev->log, err, "accept() failed");
#endif

      if (err == NGX_ECONNABORTED) {
        if (ngx_event_flags & NGX_USE_KQUEUE_EVENT) {
          ev->available--;
        }

        if (ev->available) {
          continue;
        }
      }

      return;
    }

#if (NGX_STAT_STUB)
    (void) ngx_atomic_fetch_add(ngx_stat_accepted, 1);
#endif

    ngx_accept_disabled = ngx_cycle->connection_n / 8
        - ngx_cycle->free_connection_n;

    c = ngx_get_connection(s, ev->log);

    if (c == NULL) {
      if (ngx_close_socket(s) == -1) {
        ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_socket_errno,
                      ngx_close_socket_n " failed");
      }

      return;
    }

#if (NGX_STAT_STUB)
    (void) ngx_atomic_fetch_add(ngx_stat_active, 1);
#endif

    c->pool = ngx_create_pool(ls->pool_size, ev->log);
    if (c->pool == NULL) {
      ngx_close_accepted_connection(c);
      return;
    }

    c->sockaddr = ngx_palloc(c->pool, socklen);
    if (c->sockaddr == NULL) {
      ngx_close_accepted_connection(c);
      return;
    }

    ngx_memcpy(c->sockaddr, sa, socklen);

    log = ngx_palloc(c->pool, sizeof(ngx_log_t));
    if (log == NULL) {
      ngx_close_accepted_connection(c);
      return;
    }

    /* set a blocking mode for aio and non-blocking mode for others */

    if (ngx_inherited_nonblocking) {
      if (ngx_event_flags & NGX_USE_AIO_EVENT) {
        if (ngx_blocking(s) == -1) {
          ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_socket_errno,
                        ngx_blocking_n " failed");
          ngx_close_accepted_connection(c);
          return;
        }
      }

    } else {
      if (!(ngx_event_flags & (NGX_USE_AIO_EVENT|NGX_USE_RTSIG_EVENT))) {
        if (ngx_nonblocking(s) == -1) {
          ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_socket_errno,
                        ngx_nonblocking_n " failed");
          ngx_close_accepted_connection(c);
          return;
        }
      }
    }

    *log = ls->log;

    c->recv = ngx_recv;
    c->send = ngx_send;
    c->recv_chain = ngx_recv_chain;
    c->send_chain = ngx_send_chain;

    c->log = log;
    c->pool->log = log;

    c->socklen = socklen;
    c->listening = ls;
    c->local_sockaddr = ls->sockaddr;

    c->unexpected_eof = 1;

#if (NGX_HAVE_UNIX_DOMAIN)
    if (c->sockaddr->sa_family == AF_UNIX) {
      c->tcp_nopush = NGX_TCP_NOPUSH_DISABLED;
      c->tcp_nodelay = NGX_TCP_NODELAY_DISABLED;
#if (NGX_SOLARIS)
      /* Solaris's sendfilev() supports AF_NCA, AF_INET, and AF_INET6 */
      c->sendfile = 0;
#endif
    }
#endif

    rev = c->read;
    wev = c->write;

    wev->ready = 1;

    if (ngx_event_flags & (NGX_USE_AIO_EVENT|NGX_USE_RTSIG_EVENT)) {
      /* rtsig, aio, iocp */
      rev->ready = 1;
    }

    if (ev->deferred_accept) {
      rev->ready = 1;
#if (NGX_HAVE_KQUEUE)
      rev->available = 1;
#endif
    }

    rev->log = log;
    wev->log = log;

    /*
     * TODO: MT: - ngx_atomic_fetch_add()
     *             or protection by critical section or light mutex
     *
     * TODO: MP: - allocated in a shared memory
     *           - ngx_atomic_fetch_add()
     *             or protection by critical section or light mutex
     */

    c->number = ngx_atomic_fetch_add(ngx_connection_counter, 1);

#if (NGX_STAT_STUB)
    (void) ngx_atomic_fetch_add(ngx_stat_handled, 1);
#endif

#if (NGX_THREADS)
    rev->lock = &c->lock;
    wev->lock = &c->lock;
    rev->own_lock = &c->lock;
    wev->own_lock = &c->lock;
#endif

    if (ls->addr_ntop) {
      c->addr_text.data = ngx_pnalloc(c->pool, ls->addr_text_max_len);
      if (c->addr_text.data == NULL) {
        ngx_close_accepted_connection(c);
        return;
      }

      c->addr_text.len = ngx_sock_ntop(c->sockaddr, c->addr_text.data,
                                       ls->addr_text_max_len, 0);
      if (c->addr_text.len == 0) {
        ngx_close_accepted_connection(c);
        return;
      }
    }

#if (NGX_DEBUG)
    {

      in_addr_t            i;
      ngx_event_debug_t   *dc;
      struct sockaddr_in  *sin;

      sin = (struct sockaddr_in *) sa;
      dc = ecf->debug_connection.elts;
      for (i = 0; i < ecf->debug_connection.nelts; i++) {
        if ((sin->sin_addr.s_addr & dc[i].mask) == dc[i].addr) {
          log->log_level = NGX_LOG_DEBUG_CONNECTION|NGX_LOG_DEBUG_ALL;
          break;
        }
      }

    }
#endif

    ngx_log_debug3(NGX_LOG_DEBUG_EVENT, log, 0,
                   "*%d accept: %V fd:%d", c->number, &c->addr_text, s);

    if (ngx_add_conn && (ngx_event_flags & NGX_USE_EPOLL_EVENT) == 0) {
      if (ngx_add_conn(c) == NGX_ERROR) {
        ngx_close_accepted_connection(c);
        return;
      }
    }

    log->data = NULL;
    log->handler = NULL;

    ls->handler(c);

    if (ngx_event_flags & NGX_USE_KQUEUE_EVENT) {
      ev->available--;
    }

  } while (ev->available);
}


ngx_int_t
ngx_trylock_accept_mutex(ngx_cycle_t *cycle)
{
  if (ngx_shmtx_trylock(&ngx_accept_mutex)) {

    ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                   "accept mutex locked");

    if (ngx_accept_mutex_held
        && ngx_accept_events == 0
        && !(ngx_event_flags & NGX_USE_RTSIG_EVENT))
    {
      return NGX_OK;
    }

    if (ngx_enable_accept_events(cycle) == NGX_ERROR) {
      ngx_shmtx_unlock(&ngx_accept_mutex);
      return NGX_ERROR;
    }

    ngx_accept_events = 0;
    ngx_accept_mutex_held = 1;

    return NGX_OK;
  }

  ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                 "accept mutex lock failed: %ui", ngx_accept_mutex_held);

  if (ngx_accept_mutex_held) {
    if (ngx_disable_accept_events(cycle) == NGX_ERROR) {
      return NGX_ERROR;
    }

    ngx_accept_mutex_held = 0;
  }

  return NGX_OK;
}


static ngx_int_t
ngx_enable_accept_events(ngx_cycle_t *cycle)
{
  ngx_uint_t         i;
  ngx_listening_t   *ls;
  ngx_connection_t  *c;

  ls = cycle->listening.elts;
  for (i = 0; i < cycle->listening.nelts; i++) {

    c = ls[i].connection;

    if (ngx_event_flags & NGX_USE_RTSIG_EVENT) {

      if (ngx_add_conn(c) == NGX_ERROR) {
        return NGX_ERROR;
      }

    } else {
      if (ngx_add_event(c->read, NGX_READ_EVENT, 0) == NGX_ERROR) {
        return NGX_ERROR;
      }
    }
  }

  return NGX_OK;
}


static ngx_int_t
ngx_disable_accept_events(ngx_cycle_t *cycle)
{
  ngx_uint_t         i;
  ngx_listening_t   *ls;
  ngx_connection_t  *c;

  ls = cycle->listening.elts;
  for (i = 0; i < cycle->listening.nelts; i++) {

    c = ls[i].connection;

    if (!c->read->active) {
      continue;
    }

    if (ngx_event_flags & NGX_USE_RTSIG_EVENT) {
      if (ngx_del_conn(c, NGX_DISABLE_EVENT) == NGX_ERROR) {
        return NGX_ERROR;
      }

    } else {
      if (ngx_del_event(c->read, NGX_READ_EVENT, NGX_DISABLE_EVENT)
          == NGX_ERROR)
      {
        return NGX_ERROR;
      }
    }
  }

  return NGX_OK;
}


static void
ngx_close_accepted_connection(ngx_connection_t *c)
{
  ngx_socket_t  fd;

  ngx_free_connection(c);

  fd = c->fd;
  c->fd = (ngx_socket_t) -1;

  if (ngx_close_socket(fd) == -1) {
    ngx_log_error(NGX_LOG_ALERT, c->log, ngx_socket_errno,
                  ngx_close_socket_n " failed");
  }

  if (c->pool) {
    ngx_destroy_pool(c->pool);
  }

#if (NGX_STAT_STUB)
  (void) ngx_atomic_fetch_add(ngx_stat_active, -1);
#endif
}


u_char *
ngx_accept_log_error(ngx_log_t *log, u_char *buf, size_t len)
{
  return ngx_snprintf(buf, len, " while accepting new connection on %V",
                      log->data);
}
